Effect of Ca Promoter on the Structure and Catalytic Behavior of FeK/Al₂O₃ Catalyst in Fischer‐Tropsch Synthesis

Abstract

Fischer‐Tropsch synthesis (FTS) to olefins is an alternative route for lower olefins production. The role of alkaline‐earth metals as promoters in FTS was not so clear. Herein, we prepared a series of FeKCa/Al2O3 catalysts by excessive co‐impregnation method to elucidate the promotion effect of Ca on catalytic performance. Characterization technologies of N2 physisorption, XRD, Raman spectrum, TEM and CO chemisorption were used to study the textural properties, phase composition and dispersion of Fe species. The results showed that the addition of Ca promotes dispersion of iron species thus leads to much smaller crystallite size. Meanwhile, no electron donation effect was observed upon Ca introduction, as evidenced by XPS and H2‐TPR. A maximum of FTY is achieved at 1.0 wt.% Ca, followed by a decline when adding excessive Ca due to less exposed active sites. Notably, the product distribution is almost unchanged. The nearly constant TOF values with and without Ca addition indicates Ca works only as a structural promoter rather than chemical promoter.

Carbon Pathways, Sodium‐Sulphur Promotion and Identification of Iron Carbides in Iron‐based Fischer‐Tropsch Synthesis

“…With varying the catalyst material compositions (e. g., active d-block metal, support material and structural and/or chemical promoters) the catalysts behaviour can be modified. [1,7,16,17,[8][9][10][11][12][13][14][15] General requirements for an industrially good FTS reaction catalyst material are: i) sufficient activity towards FTS reaction, ii) high selectivity for converting the input CO only to the desired hydrocarbons and iii) mechanical and catalytical stability. [4] Despite most of the d-block transition metals being somewhat active towards the FTS reaction, [1,18,19] catalysts based on Fe and Co are the most suitable ones for FTS reaction applications.…”

“…With varying the catalyst material compositions (e. g., active d‐block metal, support material and structural and/or chemical promoters) the catalysts behaviour can be modified . General requirements for an industrially good FTS reaction catalyst material are: i) sufficient activity towards FTS reaction, ii) high selectivity for converting the input CO only to the desired hydrocarbons and iii) mechanical and catalytical stability .…”

Combined In Situ X-ray Powder Diffractometry/Raman Spectroscopy of Iron Carbide and Carbon Species Evolution in Fe(−Na–S)/α-Al2O3 Catalysts during Fischer–Tropsch Synthesis

“…X-ray powder diffractometry (XRPD) is a suitable tool for characterizing the Fe carbide phases and is also widely applied in the field of FTS catalysis. ,,,,,,− Raman spectroscopy is a technique capable for differentiating between “graphitic-like”, amorphous, and fibrous carbon species − but is much less used to characterize FTS catalyst materials. − Both characterization methods can in principle also be applied under in situ or operando conditions, thereby allowing probing of the changes in the Fe phases and carbon deposit formation during the FTS reaction. Previously, such an in situ/operando Raman spectroscopy approach has been applied, e.g., to follow the formation of carbon deposits during the catalytic dehydrogenation of light alkanes , and the Co-based FTS reaction …”

Rose-Like 2D Layered Silicate Supported Fe3O4 Catalysts for Improved Selectivity Toward Olefins in CO Hydrogenation

“…However, the particles of unsupported Fe catalysts are easily sintered, and the mechanical stability of such catalysts is poor. In general, a supported catalyst can realize the dispersion and loading of the active component, deterring the particle breakage caused by coking, and has better industrial application prospects [7].…”